1. Field of the Invention
The invention relates to a calibration element for calibrating the magnification ratio of a camera, and a calibration method
2. Description of Prior Art Including Information Disclosed Under 37 CFR 1.97 and 1.98
There is known from DE 101 18 886 B4 a calibration ruler that includes a printed marking that can be detected by a camera. This marking codes the respective location such that it is also possible to determine the exact length of the detection range of the camera. This calibration ruler assumes, however, that the object to be detected is flat and is located in a defined and invariable position. In the case of product webs in the fields of textiles, papers and plastics, this condition can be fulfilled without any problem because of the negligible product web thickness, but in the case of rubber webs, however, this restriction leads to intolerable problems. It is necessary here also to take account of the influence of the web thickness on the calibration of the camera.